Diagnosis of Mucormycosis Using Frozen Section, Histopathology, Culture, and Reverse Transcriptase Polymerase Chain Reaction (RT-PCR) Techniques: A Comparative Study

Mucormycosis usually occurs in immunocompromised patients or those with uncontrolled diabetes. Along the third wave of SARS-CoV-2, an associated angioinvasive opportunistic infection with Mucor, a life-threatening fungal infection, was rampant and emerging. With an increase in the usage of steroids in the COVID scenario, the rate of mucormycosis did take a rapid and alarming increase in King Edward Memorial Hospital, Pune, India. Any delay in the diagnosis and management of the disease was life-threatening. The most conventional methods to diagnose mucormycosis are microbiological culture and histopathology of the tissue. The microbiological culture method plays an important role in the diagnosis of mucormycosis. However, the technique is labour-intensive, taking seven to eight days. Histopathology leads to false-negative reports if the tissue is not biopsied from representative sites. On the other hand, molecular methods are rapid, reliable, and applicable to different body samples, such as tissue, paraffin-embedded tissue blocks, plasma, and urine. We aimed to use a reverse transcriptase polymerase chain reaction (RT-PCR) method to detect Mucor in plasma samples. Due to a lack of availability of fresh samples, nucleic acid was extracted from the tissue sections of 69 cases diagnosed as Mucor by histopathology. These samples were subjected to RT-PCR using the MucorGenius kit (Pathonostics, Maastricht, Netherlands). A total of 57 tissue samples were sent for culture, and 49% of our cases were positive by culture and equally by RT-PCR. There was 80% sensitivity and 76% specificity between culture and PCR techniques. However, the use of blood/plasma for RT-PCR for early diagnosis of mucormycosis will be the method of choice.